There's more to the grid than just electricity

"The coal-fired power generation industry is on the brink of collapse", writes Alan Kohler. While I have a very high opinion of Mr Kohler, I think perhaps we need to talk about grid services, logistics and physics before making broad statements that solar PV and batteries will take over the NEM. The only way to get to net zero grid is by using all the tools in the low-emissions toolkit, and through careful planning. We need to meet these targets at the lowest total system cost possible, and this cannot be achieved by using one or two technologies.

For starters, we can't build enough synchronous capacity to replace the vast coal fleet that quickly. If the government is serious about emissions, and bioenergy with CCS is not an option, we will need to get rid of coal in Australia. No questions. And I very much would like to get to net zero, please. But timing and logistics will always get in the way of a good story.

However, there's a few things stopping solar PV and batteries taking over the NEM. The first is renewable droughts. Every few years, we get a great low pressure system across the country. This is 1 in 5 year wind drought for NEM. All states go down together for a week.

Assuming that the system can handle half of the usual output from wind... and making up the rest in battery storage... we would have to hold 14MWh for every MW of wind for this period. So a 1GW wind farm would need 108 of Tesla’s Hornsdale batteries (pre-expansion) to cover this. Not to mention the increase in renewable capacity that will be required to charge those batteries. That's not the best use of funds when there are much better long term storage options available. And I'm not sure how anyone will find the land in optimal spots to build all this capacity.

Now I know we're talking solar PV in this article, but how many days in a row do we have miserable weather all down the east coast? Does it happen every winter? If we get one hour of sunshine in those periods, we can either use the power from the PV OR charge the batteries... you can't do both.

A net zero grid for the NEM will consist of about 100GW of wind and solar PV. To get there, we will need the total installed capacity of 2019 (2.2GW) built every year between now and 2050. We will need to up our installation of wind, though. But this is just the VRE part. We still need to address the other services the grid needs. And sorry, but batteries aren't the technology to do this.

Each technology brings with it a set of services to the grid. Batteries are great for within-day smoothing, but for deep storage, we need pumped hydro energy storage. Snowy 2.0 is a great example of this, so is Battery of the Nation. If we were Norway, we wouldn't have to worry about a thing, but unfortunately Australia is a little bit flatter and a little bit drier.

While we're on comparing different technologies, a GW or solar PV or wind does not equal a GW of coal or gas. It's like comparing apples to blueberries. They have different things they bring to the grid. So when Mr Kohler states: "there is now 11 gigawatts of rooftop solar now installed around the country, which is equivalent to four Eraring power stations, or five Loy Yang As", these are most definitely not the same. Forgetting the grid services thing above (though that's hard because the entire system collapses without it), availability and capacity is vastly different between variable renewables and thermal plant. Not that it's a reason not to have renewables on the system. We definitely need them to reach net zero. But physics and maths will always win.

Some key take aways:

It is important to consider the whole system across all timescales to 2050 and beyond

• The value of a technology depends on existing grid
• Chasing intermediate targets whilst ignoring the long term can be suboptimal
• Energy supply is only one of several grid services

A secure grid requires a range of essential services

• Traditional grid service suppliers are disappearing
• Services need valuing to reward existing providers and attract new suppliers
• Existing plant can provide many services if flexible
• Inflexible plant will struggle to survive

The solution will be diverse

• To resolve the trilemma, a range of technologies will be required
• Each technology brings a different range of services
• Each state has unique problems and opportunities

Providing reliable low emissions electricity comes at a cost

• All low carbon energy forms are more expensive than existing assets
• Total system optimisation will lead to the lowest cost highest reliability outcomes

References here. Worth a read! Thanks Andy Boston and Geoff Bongers.